Gearbox lubrication system

ABSTRACT

According to one embodiment, a rotorcraft includes a body, a rotor blade, a drive system that can be operated to rotate the rotor blade, and an emergency valve control unit. The drive system contains a first gearbox assembly, a second gearbox assembly, a first lubrication system that can deliver lubricant to the first gearbox assembly, and a second lubrication system that can deliver lubricant to the second gearbox assembly. The drive system also contains an emergency valve that can be opened to deliver lubricant from the first lubrication system to the second gearbox assembly. The emergency valve control unit can instruct the emergency valve to open.

TECHNICAL FIELD

This invention relates generally to a rotorcraft, and more particularly,to a lubrication system for rotorcraft gearboxes.

BACKGROUND

Rotorcraft drive systems can include various components that produce andtransfer power. For example, engines and gearboxes are standardcomponents. Such components generate heat and require lubrication.Excessive levels of heat can cause premature failure and create safetyrisks. Proper lubrication serves to reduce heat generation and assist inheat removal from moving components within gearboxes.

Typically, rotorcraft use a variety of primary lubrication systems toprovide wear protection and heat transfer for moving components. Undernormal operating conditions, primary lubrication systems provide properlubrication and heat removal. However, primary lubrication systems canfail to result in excessive heat generation, wear, and failure ofcomponents, such as bearings or gears within a gearbox.

Rotorcraft are generally required to maintain manageable flightoperations for selected durations of time if the primary lubricationsystem fails. One method used to satisfy the requirements of manageableflight during a lubrication system failure is to use a secondary,emergency lubrication system to operate when the primary lubricationsystem fails. This method increases the overall weight of therotorcraft. Therefore, an improved method of controlling heat transferfrom an aircraft gearbox is desired.

SUMMARY

Particular embodiments of the present disclosure may provide one or moretechnical advantages. A technical advantage of one embodiment mayinclude the capability to deliver supplemental lubricant to a gearboxwhen the rotorcraft experiences a reduction in lubricant pressure. Atechnical advantage of one embodiment may include the capability toreduce the friction experienced by components of a gearbox when therotorcraft experiences a reduction in lubricant pressure. A technicaladvantage of one embodiment may include the capability to increase theamount of time that a rotorcraft can operate with a reduced lubricantpressure. A technical advantage of one embodiment may include theability to use preheated lubricant in the event of a lubrication systemfailure. A technical advantage of one embodiment may include thereduction of weight of the rotorcraft. A technical advantage of oneembodiment may include the reduction in maintenance burdens. A technicaladvantage of one embodiment may include the extension of lubricant life.

Certain embodiments of the present disclosure may include some, all, ornone of the above advantages. One or more other technical advantages maybe readily apparent to those skilled in the art from the figures,descriptions, and claims included herein.

BRIEF DESCRIPTION OF THE DRAWINGS

To provide a more complete understanding of the present invention andthe features and advantages thereof, reference is made to the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 shows a perspective view of a tiltrotor aircraft in helicoptermode, according to one example embodiment;

FIG. 2 shows a perspective view of a tiltrotor aircraft in airplanemode, according to one example embodiment;

FIG. 3 shows a perspective view of the drive system of the tiltrotoraircraft of FIGS. 1 and 2, according to one example embodiment;

FIG. 4 shows a schematic view of a lubrication arrangement of the drivesystem of FIG. 3, according to one example embodiment;

FIG. 5 shows a schematic view of a lubrication arrangement of the drivesystem of FIG. 3, according to one example embodiment;

FIG. 6 shows a schematic view of a lubrication arrangement of anaircraft, according to one example embodiment;

FIG. 7 shows a schematic view of a lubrication arrangement of anaircraft, according to one example embodiment; and

FIG. 8 shows a schematic view of an emergency valve control system,according to one example embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 in the drawings illustrate a tiltrotor aircraft 101,according to one example embodiment. Tiltrotor aircraft 101 can includea fuselage 103, a landing gear 105, a tail member 107, a wing 109, adrive system 111, and a drive system 113. Each drive system 111 and 113includes a fixed engine 139 and a rotatable proprotor 115 and 117,respectively. Each rotatable proprotor 115 and 117 have a plurality ofrotor blades 119 and 121, respectively, associated therewith. Theposition of proprotors 115 and 117, as well as the pitch of rotor blades119 and 121, can be selectively controlled in order to selectivelycontrol direction, thrust, and lift of tiltrotor aircraft 101.

FIG. 1 illustrates tiltrotor aircraft 101 in helicopter mode, in whichproprotors 115 and 117 are positioned substantially vertical to providea lifting thrust. FIG. 2 illustrates tiltrotor aircraft 101 in anairplane mode in which proprotors 115 and 117 are positionedsubstantially horizontal to provide a forward thrust in which a liftingforce is supplied by wing 109. It should be appreciated that tiltrotoraircraft can be operated such that proprotors 115 and 117 areselectively positioned between airplane mode and helicopter mode, whichcan be referred to as a conversion mode.

The drive system 113 is substantially symmetric to the drive system 111;therefore, for sake of efficiency, certain features will be disclosedonly with regard to drive system 111. However, one of ordinary skill inthe art would fully appreciate an understanding of drive system 113based upon the disclosure herein of drive system 111.

Further, drive systems 111 and 113 are illustrated in the context oftiltrotor aircraft 101; however, drive systems 111 and 113 can beimplemented on other tiltrotor aircraft. For example, an alternativeembodiment may include a quad tiltrotor that has an additional wingmember aft of wing 109; the additional wing member can have additionaldrive systems similar to drive systems 111 and 113. In anotherembodiment, drive systems 111 and 113 can be used with an unmannedversion of tiltrotor aircraft 101. Further, drive systems 111 and 113can be integrated into a variety of tiltrotor aircraft configurations.Additionally, other drive systems are contemplated. For example, oneexample is a gearbox arrangement to provide torque to a rotor system ofa helicopter.

FIG. 3 shows a perspective view of drive system 111, according to oneexample embodiment. Drive system 111 may include a first gearboxassembly 410 and a second gearbox assembly 420. First gearbox assembly410 may include spiral bevel gearbox 411, interconnect gearbox 412,blower gearbox 413, interconnect driveshaft 414, and engine 139 (notshown in FIG. 3). Second gearbox assembly 420 may include proprotorgearbox 421, and mast 422.

Engine 139 may be fixed relative to wing 109 of aircraft 101 and canprovide torque via an engine output shaft (not shown) to spiral bevelgearbox 411. Spiral bevel gearbox 411 can include spiral bevel gears tochange torque direction by approximately ninety degrees from engine 139to interconnect gearbox 412 via a clutch. Interconnect gearbox 412 caninclude a plurality of gears, such as helical gears, in a gear trainthat are coupled to interconnect driveshaft 414, blower gearbox 413, andsecond gearbox assembly 420. The interconnect gearbox 412 can also beconfigured to provide power to various system accessories such asalternators, lube and scavenge pumps, hydraulic pumps, and generators.

Proprotor gearbox 421 can include a plurality of gears that can beconfigured to transfer power and reduce rotational speed to mast 422.The blower gearbox 413 can be mounted to interconnect gearbox 412 andcan be configured to provide torque to the oil cooler blower fan, whichmay be used to draw in air for lubricant temperature reduction.Interconnect driveshaft 414 can be configured to provide a torque paththat enables a single engine to provide torque to both drive systems 111and 113 in the event of a failure of one of the engines.

Gears, bearings, and other mechanical components of drive system 111 aresubject to wear and heat generation due to contact with othercomponents. These mechanical components may be lubricated to reducefriction and transfer heat away from the components. Lubrication is theprocess or technique employed to reduce wear of one or both surfaces inclose proximity, and moving relative to each other, by interposing asubstance, such as a lubricant, between the surfaces to help carry theload (pressure generated) between the opposing surfaces.

A lubricant is a substance introduced to reduce friction between movingsurfaces. Examples of lubricants can include oil, biolubricants derivedfrom plants and animals, synthetic oils, solid lubricants, and aqueouslubricants. Example transmission oils for gearbox 160 may include oilsmeeting specifications MIL-PRF-23699 (5 cSt), DOD-L-7808 (3-4 cSt),DOD-PRF-85734 (5 cSt), and other oils in the 9 cSt to 10 cSt viscosityrange. Drive system 111 may include one or more lubrication systems toprovide lubricant to the mechanical components of drive system 111.

FIG. 4 shows a schematic view of a lubrication arrangement 500 a ofdrive system 111, according to one example. Lubrication arrangement 500a can include a first lubrication system 510 and a second lubricationsystem 520. Lubrication system 510 may provide lubricant to componentsof first gearbox assembly 410, whereas lubrication system 520 mayprovide lubricant to components of second gearbox assembly 420.Lubrication system 510 can include lubricant tank 511, pump 512, heatexchanger 513, filter 514, and lubrication lines 10 through 17.Lubrication system 520 may include lubricant tank 521, pump 522, heatexchanger 523, filter 524, and lubrication lines 20 through 25.Lubrication systems 510 and 520 may also include other components suchas one or more sensors 610, pressure regulators, flowmeters, checkvalves, and jets, which are not depicted in the schematic view of FIGS.4 and 5.

Tanks 511 and 521 may represent reservoirs that store lubricant withinlubrication systems 510 and 520, respectively. Tanks 511 and 521 may beintegral with the housing of one of the gearboxes, such as interconnectgearbox 412 or proprotor gearbox 421, or separate from the housings ofthe gearboxes. Pumps 512 and 522 may represent devices that can beconfigured to circulate pressurized lubricant throughout lubricationsystems 510 and 520, respectively. Heat exchangers 513 and 523 may bedevices configured to lower the temperature of the lubricant before thelubricant is applied to the various components that generate heat.Filters 514 and 524 may represent devices configured to removecontaminants from the lubricant. Jets, which are not shown in theschematic views of FIGS. 4 and 5, may be devices configured to dispenselubricant on components of drive system 111 that are subject to frictionand/or generate heat, such as gears and bearing.

Sensors 610, which are not shown in the schematic view of FIGS. 4 and 5,may represent devices that can be configured to detect one or morerotorcraft parameters output by rotorcraft 101. For example, lubricationarrangement 500 a may include one or more pressure sensors 610 that candetect the pressure of the lubricant within lubrication system 510 or520. Examples of pressure sensors may include strain-gauge sensors,capacitive sensors, electromagnetic sensors, piezoelectric sensors,optical sensors, potentiometric sensors, resonant sensors, and thermalsensors, to name a few. In another example embodiment, lubricationarrangement 500 a may include one or more temperature sensors that candetect the temperature of the lubricant in lubrication system 510 or520. It should be noted that rotorcraft 101, drive system 111, orlubrication arrangement 500 a may include a plurality of sensors thatare of different types. For example, lubrication arrangement 500 a caninclude both a pressure sensor and a temperature sensor.

Lubrication lines 10 through 17 and 20 through 25 may represent fluidlines that connect various components of lubrication system 510 and 520.Lubrication lines 10 through 17 and 20 through 25 may represent rigidpipelines, such as core passages in the housing of a gearbox, orflexible hoses, such as fluoropolymer tubing. The type of lubricationlines used may depend on the location of the line or expected fluidpressure within the line. Lubrication lines 10 through 17 and 20 through25 may include other components such as swivels and quick disconnectcouplings. In some examples, lubrication lines 10 through 17 and 20through 25 may be collapsible in order to reduce residual lubricantduring storage and when lubricant is not being flowed through the line.

As mentioned, lubrication lines 10 through 17 and 20 through 25 mayfluidly connect various components of lubrication system 510 or 520.Lubrication lines 10 through 17 may fluidly connect components oflubrication system 510. For example, as can be seen in FIGS. 4 and 5,pump 512 may deliver lubricant from tank 511 into lubrication line 10.The lubricant may then travel from lubrication line 10 to heat exchanger513 where the lubricant is cooled. Next, the lubricant may travel fromheat exchanger 513, through line 11, to filter 514 where particles maybe removed from the lubricant. From filter 514, the lubricant may travelthrough line 12 to one or more gearboxes within lubrication system 510,such that the lubricant gets delivered to moving components within theone or more gearboxes. The lubricant then, after traveling through lines13 through 17, returns to tank 511.

Lubrication lines 20 through 25 may fluidly connect components oflubrication system 520. For example, pump 522 may deliver lubricant fromtank 521 to lubricant line 20, from line 20 to heat exchanger 523 wherethe lubricant is cooled. From heat exchanger 523, the lubricant may thenbe delivered to filter 524, via line 21, where particles may be removedfrom the lubricant. From filter 524, the lubricant may travel throughline 22 to oil tank 521.

Under normal operating conditions, lubrication systems 510 and 520provide proper lubrication to the moving components of first gearboxassembly 410 and second gearbox assembly 420, respectively. Thelubricant pressure within the gearboxes of first gearbox assembly 410and second gearbox assembly 420 may be at a normal level, for example,fifty PSI (pounds per square inch). Additionally, during normaloperating conditions, first lubrication system 510 may not be in fluidcommunication with second lubrication system 520.

If for example, proper lubrication is not provided to the movingcomponents of gearbox assemblies 410 or 420 or lubrication system 510 or520 experience a loss of lubrication, the moving components of gearboxassembly 410 or 420 may experience excessive wear or the failure ofcomponents. One example cause of a loss of lubrication may be a leakbetween the casing of one of the gearboxes and one of its components. Insome loss of lubrication circumstances, the lubricant pressure within agearbox of gearbox assembly 410 or 420 may be reduced to an undesiredlevel. For example, the pressure may drop below thirty PSI, and in someinstances may drop to zero PSI.

Rotorcraft are generally required to maintain manageable flightoperations for selected durations of time if the rotorcraft experienceslow lubricant pressure, such as during a loss of lubrication situationor lubrication system failure. For example, an aviation agency mayrequire that the loss of lubrication will not prevent continued safeoperation for at least thirty minutes after perception by the flightcrew of the lubrication system failure or loss of lubrication.Therefore, some rotorcraft may also include a secondary lubricationsystem, such as emergency lubrication system 530.

Emergency lubrication system 530 may represent a system that has asecondary lubricant tank and a pressurizing device. The lubricant tankof emergency lubrication system 530 may represent a reservoir configuredto contain lubricant. In one example, the lubricant tank of emergencylubrication system 530 may be configured to contain approximately sevengallons of lubricant. Examples of a pressurizing device that can be usedin emergency lubrication system 530 may be a mechanically driven pump, ahydraulically driven pump, an electrically driven pump, or a gravityfeed system.

In a loss of lubrication event, lubricant may be introduced from theemergency lubrication system 530 to the working components of gearboxassembly 410 and/or 420. Lubricant may be provided from the secondarylubrication tank of emergency lubrication system 530 to gearbox assembly410 through lubrication lines 30 through 32 and emergency line jets (notshown), and/or to gearbox assembly 420 through lubrication lines 33 andemergency line jets (not shown).

Even though the use of emergency lubrication system 530 has someadvantages, such as increasing the amount of time the rotorcraft isoperable, this method may have some potential disadvantages, such asincreasing the weight of the aircraft due to the extra tank, pump, andlubricant that may be included in emergency lubrication system 530.Therefore, a new system and method for providing emergency lubricationis needed.

FIG. 5 shows a schematic view of a lubrication arrangement 500 b,according to one example embodiment. Lubrication arrangement 500 bfeatures emergency lubrication system 540. Emergency lubrication system540 can include emergency lubrication lines 40 through 45, valves 541and 542, and one or more emergency jets (not shown).

Emergency lubrication lines 40 through 45 may represent rigid pipelines,such as core passages in the housing of a gearbox, or flexible hoses,such as fluoropolymer tubing. The type of lubrication lines used maydepend on the location of the line or expected fluid pressure within theline. Lubrication lines 40 through 45 may include other components suchas swivels and quick disconnect couplings. Lubrication lines 40 through45 can be configured such that they deliver lubricant to emergency jets(not shown).

Valves 541 and 542 can represent devices that regulate the flow of afluid by opening or closing a passageway. In one example, valve 541and/or 542 can be a solenoid valve that can be electromechanicallyoperated. An electric current may control the solenoid valve, and thevalve can be switched open to allow a flow of lubricant or closed tostop a flow of lubricant.

In one example embodiment, emergency lubrication system 540 does notinclude an extra lubrication tank that provides lubricant to gearboxassembly 410 and/or gearbox assembly 420. However, extra lubricant canbe stored within tank 511 and/or tank 521. For example, two extragallons may be stored within tank 511, and seven extra gallons may bestored within tank 521.

During a loss of lubrication event in one of the gearbox assemblies, alubrication system that under normal operating conditions supplieslubricant to another gearbox assembly may also supply lubricant to thegearbox assembly that is experiencing a loss of lubrication event. Forexample, if second gearbox assembly 420 experiences a loss oflubrication event, lubricant can be supplied to second gearbox assembly420 by lubrication system 510 by opening valve 541.

Lubricant may flow from lubrication system 510 to lubricant line 40,from line 40 to valve 541, from valve 541 to line 41, from line 41 togearbox assembly 420. The flow of lubricant can be caused by thepressure of lubricant in lubrication system 510 that is created by pump512 of lubrication system 510. In one example, emergency jets can beused to supply the lubricant from lubrication system 510 to gearboxassembly 420. The emergency jets may allow for a slower flow rate oflubricant than the normal operating jets in order to conserve lubricant.

If gearbox assembly 410 experiences loss of lubrication, valve 542 canbe opened to allow a flow of lubricant from lubrication system 520 togearbox assembly 410. Lubricant may flow from lubrication system 520 tolubrication line 42, from line 42 to valve 542, from valve 542 to line43, from line 43 to lines 44 and 45, from lines 44 and 45 to gearboxassembly 410. The flow of lubricant can be caused by the pressure oflubricant in lubrication system 520 that is created by pump 522 oflubrication system 520. In one example, emergency jets can be used tosupply the lubricant from lubrication system 510 to gearbox assembly410. The emergency jets may allow for a slower flow rate of lubricantthan the normal operating jets in order to conserve lubricant.

FIG. 6 shows a schematic view of a lubrication arrangement 500 c of anaircraft according to one example embodiment. In this example, aircraft101 features a third gearbox assembly 430 located between drive system111 and drive system 113. Torque from drive system 111 can betransferred from first gearbox assembly 410, through interconnect driveshaft 414, to third gearbox assembly 430. Torque from drive system 113can also be transferred from first gearbox assembly 410, throughinterconnect drive shaft 414, to third gearbox assembly 430. In theevent of an engine failure, power from one of drive system 111 or drivesystem 113 can be distributed to the other through the interconnectdrive shafts 414 and the third gearbox assembly 430.

Third gearbox assembly 430 can have a lubrication system, such aslubrication system 550, that includes components such as a pump, heatexchanger, filter, tank, and lubrication lines. Under normal operatingconditions, lubrication system 550 provides proper lubrication to themoving components of gearbox assembly 430 and the lubricant pressurewithin gearbox 430 may be at a normal level. During normal operatingconditions, lubrication system 550 may not supply lubricant to gearboxassembly 410 or 420.

If for example, proper lubrication is not provided to the movingcomponents of gearbox assembly 430 or lubrication system 550 experiencesa loss of lubrication, lubricant can be shared from lubrication system510 and/or 520 to gearbox assembly 430, via emergency lubrication system560, according to one example embodiment.

For example, if gearbox assembly 430 experiences loss of lubrication,valve 543 can be opened to allow a flow of lubricant from lubricationsystem 510 to gearbox assembly 430. Lubricant may flow from lubricationsystem 510 to lubricant line 52, from line 52 to valve 543, from valve543 to line 53, and from line 53 to gearbox assembly 430. The flow oflubricant can be caused by the pressure of lubricant in lubricationsystem 510 that is created by pump 512 of lubrication system 510.Additionally, valve 542 can also be opened to allow a flow of lubricantfrom lubrication system 520 to lubrication system 510, from lubrication510 to gearbox assembly 430.

Similarly, if lubrication system 510 and/or 520 experience a loss oflubrication, valve 544 can be opened to allow a flow of lubricant fromlubrication system 550 to lubrication system 510. Lubricant may flowfrom lubrication system 550 to lubricant line 50, from line 50 to valve544, from valve 544 to line 51, and from line 51 to lubrication system510. Additionally, valve 541 can also be opened to allow a flow oflubricant from lubrication system 550 to lubrication system 510, fromlubrication system 510 to gearbox assembly 420.

In one example embodiment, lubricant from lubrication systems 510, 520,and 550 is shared when neither lubrication system 510, 520, nor 550 areexperiencing loss of lubrication. The sharing of lubricant innon-emergency situations may have several advantages. First, the sharingof lubricant between the lubrication systems may extend the life of thelubricant. For example, because some of the gearboxes, such as gearbox411, may increase the temperature of the lubricant more than othergearboxes, such as gearbox 412, the lubricant is allowed to cool withinthe gearboxes that produce less heat. Additionally, lubricant may alsobe cooled by convection via the lubricant lines that run along the wingof rotorcraft 101.

Second, when lubricant is shared between the lubrication systems, it mayreduce the frequency of lubricant changes. For example, lubricant mayhave to be changed more often in gearboxes that generate more heat thanin gearboxes that generate less heat. Third, the sharing of lubricantbetween lubrication systems may reduce the number of sensors, such asoil quality sensors. For example, if lubricant was shared between thelubrication systems, it may only be necessary to have one oil qualitysensor, as opposed to one oil quality sensor for each lubricationsystem.

Lubrication arrangement 500 c can have lubrication systems 510, 520, and550 fluidly connected in series. However, teachings of certain exampleembodiments recognize that it may be beneficial to have lubricationsystems 510, 520, and 550 fluidly connected in parallel.

FIG. 7 shows a schematic view of a lubrication arrangement 500 d of anaircraft, according to one example embodiment. Lubrication arrangement500 d is similar to lubrication arrangement 500 c. However, the exampleof lubrication arrangement 500 d has lubrication systems 510, 520, and550 in parallel. Lubrication arrangement 500 d may include all the samecomponents as lubrication 500 c. Lubrication arrangement 500 d may alsoinclude valves 545 through 548 and lines 54 through 61. In this example,lubricant may be shared directly from lubrication system 550 tolubrication system 520, and vice-versus. Having the lubrication systemsconnected in parallel may be beneficial if two or more gearboxassemblies experience a loss of lubrication.

FIG. 8 shows a schematic view of an emergency valve control system 600,according to one example embodiment. Emergency valve control system 600can include an emergency valve control unit 620 that can be configuredto receive data 615 from one or more sensors 610 of aircraft 101.Emergency valve control unit 620 may also be configured to sendinstructions 625 to valves 541 through 548. Emergency valve control unit620 may represent a computer that is configured to receive data 615;data 615 may represent one of more rotorcraft parameters, such as thepressure of lubricant within lubrication system 510, 520, or 550, or thetemperature of the lubricant in lubrication system 510, 520, or 550.

Emergency valve control unit 620 may analyze data 615 to determinewhether a loss of lubricant event has occurred. In one exampleembodiment, emergency valve control unit 620 may analyze data 615 todetermine whether the loss of lubricant event occurred within gearboxassemblies 410, 420, or 430.

Emergency valve control unit 620 may analyze data 615 by comparing data615 to a threshold value. In one example embodiment, the threshold valuemay be a specific pressure within first lubrication system 510, such asthirty PSI. Therefore, emergency valve control unit 620 may receive andmonitor the lubricant pressure within first lubrication system 510 andcompare it to the threshold value of thirty PSI. If the pressure withinfirst lubrication system 510 is reduced to a value less than thirty PSI,emergency valve control unit 620 would instruct valve 542 and/or valve544 to open in order to allow supplemental lubrication to be provided tothe working components of gearbox 410.

During a loss of lubricant event within lubrication system 510,emergency valve control unit 620 may send an instruction 625 to valve542 and/or 544 to open. During a loss of lubricant event withinlubrication system 520, emergency valve control unit 620 may send aninstruction 625 to valve 541 and/or 544 to open. During a loss oflubricant event within lubrication system 550, emergency valve controlunit 620 may send an instruction 625 to valve 542 and/or 543 to open.Emergency valve control unit 620 may also send an instruction 625 tovalve 541, 542, and/or 543 to close.

Emergency valve control unit 620 may also receive and analyze data fromgearboxes that are not experiencing a loss of lubrication. For example,emergency valve control unit 620 may receive information from lubricantmonitoring sensors that detect the level of lubricant in a non-failinglubrication system that is supplying lubricant to a failing lubricationsystem. If the level of lubricant in a non-failing lubrication system isreduced to a level below a threshold value, emergency valve control unit620 may send an instruction to the emergency valve to close or reducethe flow of lubricant to the failing lubrication system.

Teachings of certain embodiments recognize that emergency valve controlunit 620 may be implemented by one or more computers 10 communicatingacross one or more networks 30 and accessible by a user 5. An example ofcomputer system 10 may include, but is not limited to, a flight controlcomputer installed on board an aircraft such as rotorcraft 101. Invarious embodiments, elements of emergency valve control unit 620 may beinstalled on board an aircraft, off-board (such as at a groundfacility), or a combination of the two. For example, in one embodiment,some elements of emergency valve control unit 620 are installed on boardthe aircraft whereas other elements of emergency valve control unit 620are installed off-board such that an onboard computer may include thecapability to determine the appropriate instruction 625 during flight aswell as the capability to upload/download information to an offboardcomputer between flights.

Computer system 10 may be used by emergency valve control unit 620 toinput the data 615 from one or more sensor 610, determine whether tosend an instruction 625 to valves 541, 542, and/or 543, and instructvalves 541, 542, and/or 543 to open or close. Users 5 may accessemergency valve control unit 620 through computer systems 10. Users 5may include any individual, group of individuals, entity, machine,and/or mechanism that interacts with computer systems 10. Examples ofusers 5 include, but are not limited to, a pilot, service person,engineer, technician, contractor, agent, and/or employee. Users 5 may beassociated with an organization. An organization may include any socialarrangement that pursues collective goals. One example of anorganization is a business. A business is an organization designed toprovide goods or services, or both, to consumers, governmental entities,and/or other businesses.

Computer system 10 may include processors 12, input/output devices 14,communications links 16, and memory 18. In other embodiments, computersystem 10 may include more, less, or other components. Computer system10 may be operable to perform one or more operations of variousembodiments. Although the embodiment shown provides one example ofcomputer system 10 that may be used with other embodiments, such otherembodiments may utilize computers other than computer system 10.Additionally, embodiments may also employ multiple computer systems 10or other computers networked together in one or more public and/orprivate computer networks, such as one or more networks 30.

Processors 12 represent devices operable to execute logic containedwithin a medium. Examples of processor 12 include one or moremicroprocessors, one or more applications, and/or other logic. Computersystem 10 may include one or multiple processors 12.

Input/output devices 14 may include any device or interface operable toenable communication between computer system 10 and external components,including communication with a user or another system. Exampleinput/output devices 14 may include, but are not limited to, a mouse,keyboard, display, and printer.

Network interfaces 16 are operable to facilitate communication betweencomputer system 10 and another element of a network, such as othercomputer systems 10. Network interfaces 16 may connect to any number andcombination of wireline and/or wireless networks suitable for datatransmission, including transmission of communications. Networkinterfaces 16 may, for example, communicate audio and/or video signals,messages, internet protocol packets, frame relay frames, asynchronoustransfer mode cells, and/or other suitable data between networkaddresses. Network interfaces 16 connect to a computer network or avariety of other communicative platforms including, but not limited to,a public switched telephone network (PSTN); a public or private datanetwork; one or more intranets; a local area network (LAN); ametropolitan area network (MAN); a wide area network (WAN); a wirelineor wireless network; a local, regional, or global communication network;an optical network; a satellite network; a cellular network; anenterprise intranet; all or a portion of the Internet; other suitablenetwork interfaces; or any combination of the preceding.

Memory 18 represents any suitable storage mechanism and may store anydata for use by computer system 10. Memory 18 may comprise one or moretangible, computer-readable, and/or computer-executable storage medium.Examples of memory 18 include computer memory (for example, RandomAccess Memory (RAM) or Read Only Memory (ROM)), mass storage media (forexample, a hard disk), removable storage media (for example, a CompactDisk (CD) or a Digital Video Disk (DVD)), database and/or networkstorage (for example, a server), and/or other computer-readable medium.

In some embodiments, memory 18 stores logic 20. Logic 20 facilitatesoperation of computer system 10. Logic 20 may include hardware,software, and/or other logic. Logic 20 may be encoded in one or moretangible, non-transitory media and may perform operations when executedby a computer. Logic 20 may include a computer program, software,computer executable instructions, and/or instructions capable of beingexecuted by computer system 10. Example logic 20 may include any of thewell-known OS2, UNIX, Mac-OS, Linux, and Windows Operating Systems orother operating systems. In particular embodiments, the operations ofthe embodiments may be performed by one or more computer readable mediastoring, embodied with, and/or encoded with a computer program and/orhaving a stored and/or an encoded computer program. Logic 20 may also beembedded within any other suitable medium without departing from thescope of the invention.

Various communications between computers 10 or components of computers10 may occur across a network, such as network 30. Network 30 mayrepresent any number and combination of wireline and/or wirelessnetworks suitable for data transmission. Network may, for example,communicate internet protocol packets, frame relay frames, asynchronoustransfer mode cells, and/or other suitable data between networkaddresses. Network 30 may include a public or private data network; oneor more intranets; a local area network (LAN); a metropolitan areanetwork (MAN); a wide area network (WAN); a wireline or wirelessnetwork; a local, regional, or global communication network; an opticalnetwork; a satellite network; a cellular network; an enterpriseintranet; all or a portion of the Internet; other suitable communicationlinks; or any combination of the preceding. Although the illustratedembodiment shows one network 30, teachings of certain embodimentsrecognize that more or fewer networks may be used and that not allelements may communicate via a network. Teachings of certain embodimentsalso recognize that communications over a network is one example of amechanism for communicating between parties, and any suitable mechanismmay be used.

Lubrication arrangements 500 b through 500 d and emergency lubricationsystems 540 and 560 are illustrated in the context of drive system 111and 113; however, lubrication arrangement 500 b through 500 d andemergency lubrication systems 540 and 560 can be implemented on othertypes of aircraft. For example, an alternative embodiment may include ahelicopter that has two or more gearboxes.

Lubrication arrangements 500 b through 500 d may have several advantagesover lubrication arrangement 500 a. One advantage may be the ability touse preheated oil in the event a loss of lubrication occurs in one ofthe lubrication systems. For example, if valve 542 is opened such thatlubricant is allowed to flow from lubrication system 520 to lubricationsystem 510, the lubricant will be preheated because it was alreadycirculating within lubrication system 520.

Another advantage of lubrication arrangements 500 b through 500 d may bethe reduction of weight over lubrication arrangement 500 a. For example,some embodiments recognize the ability to use existing oil pumps andreservoirs within the lubrication systems, as opposed to the separatetank and pump that may be included in lubrication arrangement 500 a.

Modifications, additions, or omissions may be made to the systems andapparatuses described herein without departing from the scope of theinvention. The components of the systems and apparatuses may beintegrated or separated. Moreover, the operations of the systems andapparatuses may be performed by more, fewer, or other components. Themethods may include more, fewer, or other steps. Additionally, steps maybe performed in any suitable order.

Although several embodiments have been illustrated and described indetail, it will be recognized that substitutions and alterations arepossible without departing from the spirit and scope of the presentinvention, as defined by the appended claims.

To aid the Patent Office, and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants wishto note that they do not intend any of the appended claims to invokeparagraph 6 of 35 U.S.C. § 112 as it exists on the date of filing hereofunless the words “means for” or “step for” are explicitly used in theparticular claim.

1.-20. (canceled)
 21. A rotorcraft comprising: a drive system, the drivesystem comprising: a first gearbox assembly; a second gearbox assembly,wherein the first gearbox assembly is in mechanical communication withthe second gearbox assembly; a first lubrication system associated withthe first gearbox assembly; a second lubrication system associated withthe second gearbox assembly; a valve operable to allow lubricant to bedelivered from the first lubrication system to the second gearboxassembly when the valve is open; and a control unit operable, at leastin part, to instruct the valve to open or close.
 22. The rotorcraft ofclaim 21, wherein the first lubrication system and the secondlubrication system are not in fluid communication when the valve isclosed.
 23. The rotorcraft of claim 21, wherein control unit is furtheroperable, at least in part, to: receive a rotorcraft parameter; comparethe rotorcraft parameter to a threshold value; and instruct the valve toopen when the rotorcraft parameter is less than the threshold value. 24.The rotorcraft of claim 23, wherein the rotorcraft parameter is at leastone of a pressure or a level associated with lubricant within the secondlubrication system.
 25. The rotorcraft of claim 21, wherein the valve isa solenoid valve.
 26. The rotorcraft of claim 21, wherein the drivesystem is operable to rotate a rotor blade.
 27. The rotorcraft of claim21, wherein the drive system is operable to provide power to one or moreaccessory devices.
 28. The rotorcraft of claim 21, wherein the firstlubrication system comprises: a pump; a filter; and at least onelubrication line; and the second lubrication system comprises: a pump; afilter; and at least one lubrication line.
 29. The rotorcraft of claim21, wherein the valve is a first valve, the drive system furthercomprising: a second valve operable to allow lubricant to be deliveredfrom the second lubrication system to the first gearbox assembly whenthe second valve is open, wherein the control unit is further operable,at least in part, to instruct the second valve to open or close.
 30. Therotorcraft of claim 29, the drive system further comprising: a thirdgearbox assembly; a third lubrication system associated with the thirdgearbox assembly; and a third valve operable to allow lubricant to bedelivered from the first lubrication system to the third gearboxassembly, wherein the control unit is further operable, at least inpart, to instruct the third valve to open or close.
 31. The rotorcraftof claim 30, wherein the drive system is a first drive system, therotorcraft further comprising: a second drive system, the second drivesystem further comprising: a first gearbox assembly; a second gearboxassembly, wherein the first gearbox assembly is in mechanicalcommunication with the second gearbox assembly; a first lubricationsystem associated with the first gearbox assembly; a second lubricationsystem associated with the second gearbox assembly; and a valve operableto allow lubricant to be delivered from the first lubrication system tothe second gearbox assembly when the valve is open, wherein the controlunit is further operable, at least in part, to instruct the valve toopen or close.
 32. The rotorcraft of claim 31, wherein the second drivesystem is operable to rotate a rotor blade.
 33. The rotorcraft of claim31, wherein the second drive system is operable to provide power to oneor more accessory devices.
 34. The rotorcraft of claim 31, wherein thevalve of the second drive system is a solenoid valve.
 35. The rotorcraftof claim 31, wherein the first lubrication system of the second drivesystem comprises: a pump; a filter; and at least one lubrication line;and the second lubrication system of the second drive system comprises:a pump; a filter; and at least one lubrication line.
 36. The rotorcraftof claim 31, further comprising: an interconnect driveshaft, wherein theinterconnect driveshaft is in mechanical communication with the thirdgearbox assembly and the interconnect driveshaft is in mechanicalcommunication with the first gearbox assembly of the second drivesystem.
 37. The rotorcraft of claim 36, further comprising: a firstengine in mechanical communication with the first drive system; and asecond engine in mechanical communication with the second drive system.38. The rotorcraft of claim 37, wherein the first drive system isoperable to provide power to the second drive system via theinterconnect driveshaft when the second engine is inoperable.
 39. Therotorcraft of claim 37, wherein the second drive system is operable toprovide power to the first drive system via the interconnect driveshaftwhen the first engine is inoperable.
 40. The rotorcraft of claim 21,wherein the control unit is a computing device comprising: at least onememory element operable to store data; and at least one processoroperable to execute instructions associated with the data.